The Side Effects of Yoga

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Intro: This is the last video in a six-part series on yoga. If you missed any, check the links in the description below. You’ll also find a link to the webinar that I did on this subject, which includes a Q&A portion. 

Even though for certain health conditions we have not reached a point where we can say there is good scientific evidence that yoga is beneficial, many patients do seem to benefit. And isn’t that what matters? I mean, even in the studies that show that the benefit is mainly a placebo effect, does this really matter? After all, this editorial asserted, yoga therapy has never been shown to have adverse effects. But that’s simply not true. About 2,000 yoga-related injuries were seen in hospital emergency rooms every year from 2001 to 2014.

It looks like one fatality has ever been reported in the medical literature. But if you look at the case report, a 16-year-old girl collapsing with a ruptured lung following voluntary mouth-to-mouth yoga breathing exercises with a teen-age boy in the hall, that can hardly be characterized as a typical yoga practice.

There are tragic rare cases tied to actual yoga, like this quad rupture in a young woman or, God, a femoral fracture. The femur is the bone in your thigh—longest, strongest and heaviest bone in the body. Typically, you only see femur fractures with trauma, such as car crashes, but here it was just a guy practicing this yoga posture when he heard a large cracking sound and felt immense pain because yikes, this is what happened.

Now, two weeks earlier, he felt a pain in his thigh that he just thought was muscle strain, but bone biopsies showed evidence of previous microfractures. So, it sounds like he had been overdoing it, weakening it before the final crack. So, I guess the bottom line is that people should listen to their bodies and not to push themselves too far.

Now, in my last video I talked about the risk of spinal compression fractures, particularly those with weakened bones, osteopenia, or osteoporosis. Poses causing hyperflexion and hyperextension of the spine should probably be avoided. These were the poses tied to injury in a few dozen cases of musculoskeletal injuries described at the Mayo Clinic. But case reports, and series of case reports, are really just kind of like glorified anecdotes. They don’t give you an overall sense of the safety of yoga. If you look at randomized controlled yoga trials, there’s actually no significant difference in injury rates between the yoga groups and the control groups that used some other sort of exercise intervention.

Now, this may not necessarily translate out into real-world experience, given the short duration of yoga in these clinical trials—as little as a single day—and the fact that they may be more closely supervised, with more highly trained teachers. That’s why large-scale surveys like this can be helpful, looking at thousands of people taking yoga classes.

Looks like about 30 percent of yoga class attendees had experienced some type of adverse event, most commonly just something mild like muscle aches. But some individuals did experience more severe events, which caused them to stop going. Many causes were associated with “overexertion and overdoing” and starting out in “poor physical condition.”

This systematic review included nine observational studies with 9,000+ yoga practitioners and 9,000+ non-yoga practitioners from the US, Europe, Asia, and Australia. A considerable proportion of yoga practitioners experienced injuries or other adverse events. However, most were mild and transient, and risks were comparable to those of non-yoga practitioners. The risk of yoga-associated injuries was estimated as 1.45 per thousand hours of yoga practice––much lower than in higher-impact sports activities, such as soccer. Compared to 1.5 for yoga, runners have like 2.5 injuries per thousand hours; soccer 3.7; 5 for tennis, and an hour of yoga is more than five times safer than skiing.

Here’s where yoga falls on the spectrum. Yoga appears much safer, for example, than aerobic funk. On the other hand, yoga practitioners may suffer an increased risk of meniscus injury––the main stabilizing and cushioning cartilage in the knee. Yoga was found associated with significantly higher risk of meniscus injury compared with activities such as badminton, jogging, and climbing hills. Some fundamental yoga postures, like the lotus position, can be hard on the knees. Yes, yoga poses can undoubtedly improve the flexibility of the knee, but immoderate joint movement can pose a serious threat.

The bottom line is that like any other type of physical activity, yoga carries a risk of injury. Exercise is indeed medicine, but like any medicine, it must be prescribed appropriately. Many patients rely on their yoga practice for stress reduction. So, it is important to be mindful that being injured is the last thing you need. The higher-risk yoga poses appear to include headstand, shoulder stand, lotus and half-lotus, forward bend, backward bend, and handstand. And so, beginners should be beware, with particular attention paid to the spine, as this is where the highest number of injuries occur.

Hot yoga deserves special mention. The extreme heat and intensity of Bikram yoga may make it inappropriate for older adults and people with medical conditions. But there are case reports, like this one, of sudden cardiac arrest even in a healthy 35-year-old. Pregnancy is an especially vulnerable time for heat exposure. With the increased risk of spinal defects and possibly of other birth defects among fetuses exposed to excessive heat, pregnant women should avoid practicing hot yoga during pregnancy. Maternal hyperthermia—whether from a sauna or electric blankets––had nearly a two-fold increased risk of spinal and brain malformations. For example, pregnant women who use hot tubs increase the risk of bearing babies with their intestines outside their bodies, or being born without a brain.

As with any other physical or mental practice, yoga should be practiced carefully under the guidance of a qualified instructor. Beginners should avoid extreme practices such as headstand, lotus position, and forceful breathing. Individuals with medical preconditions should work with their physician and yoga teacher to appropriately adapt postures. For example, patients with glaucoma should avoid upside-down positions, and patients with compromised bones should avoid forceful yoga practices, and practices like voluntary vomiting should perhaps be avoided completely. What? It’s evidently common practice in traditional yoga.

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Motion graphics by Avo Media

• bone health
• bone loss
• exercise
• lifestyle medicine
• muscle health
• osteoporosis
• placebo effect
• pregnancy
• side effects
• stress
• women's health
• yoga